1. Field of the Invention
The present invention relates generally to antennas, and more especially to multi-band frequency antennas including a slot antenna and a loop antenna.
2. The Related Art
Antennas are used in various communication systems, such as cellular phones, wireless data and local area network, global system for mobile communications (GSM), and personal communication service (PCS), etc. A clear and strong signal is critical for the wireless communication systems. Therefore, antennas with good performance are required.
As shown in FIG. 3, a conventional antenna 100 comprises a first element 70 and a second inverted-L element 80. The first element 70 and the second inverted-L element 80 are connected at a first portion and a second portion of the first element 70. A feed point 71 is disposed on the first portion and a grounding point 72 is disposed on the second portion.
When the conventional antenna 100 is working for communicating, the first element 70 resonates at a first frequency, and the second inverted-L element 80 resonates at a second frequency. However, while the second inverted-L element 80 is resonating, the first element 70 also resonates at a certain extend which affects the performance of the second inverted-L element 80. So when the second inverted-L element 80 receives/sends signals, the performances of radiation are not efficient so as to affect the performance of the antenna 100. In order to improve the performance of the antenna 100, tuner components (such as resistances, capacitors etc.) are applied. For example, a first tuner component 73 is coupled with the feed point 40, and a second tuner component 74 is coupled with the grounding point 50. Therefore, the performance of the antenna 100 is improved after the first and second tuner components 73, 74 being coupled with the antenna 100.
As described above, the conventional antenna 100 needs two extra tuner components 73, 74 to improve the performance. Thus, the structure of the antenna 100 is complicated with high cost, and the complicated structure of the antenna 100 is inconvenient for installation so as to affect the performance of the antenna 100.